BOSTON - Offering his own life as an example of uniquely American possibilities, Barack Obama - the son of a white woman from Kansas and a black man from Kenya - drew roars of approval from Democrats on Tuesday night, saying Americans must not allow "spin masters and negative ad peddlers" to divide the country.

"I say to them tonight, there's not a liberal America and a conservative America - there's the United States of America," said the 42-year-old candidate for a Senate seat from Illinois. The energized crowd - some chanting his name - cheered the convention keynoter and waved blue-and-white Obama signs.

He said people don't expect government to solve all their problems but sometimes do need help.

"They sense, deep in their bones, that with just a slight change in priorities we can make sure that every child in America has a decent shot at life and that the doors of opportunity remain open to all," Obama said in his keynote address.

He said John Kerry would provide that change at home - and lead America into war abroad only when absolutely necessary.

"When we send our young men and women into harm's way, we have a solemn obligation not to fudge the numbers or shade the truth about why they're going," Obama said in a jab at President Bush, "and to never - ever - go to war without enough troops to win the war, secure the peace and earn the respect of the world."

The crowd leapt to its feet in cheers.

Obama's father was a goat herder in Africa who won a scholarship to study in America. He described his mother's youth in Kansas, raised by a couple who built a good life with educations they obtained through the GI Bill and a home they got with a federal loan.

"My parents shared not only an improbable love, they shared an abiding faith in the possibilities of this nation," Obama said.

Obama would become the Senate's only black member, and only the fifth black senator in history, if elected this fall. Harvard educated, Obama is a state senator who teaches law at the University of Chicago.

He urged parents to "turn off the television sets and eradicate the slander that says a black youth with a book is acting white."

This is the second convention in a row in which Democrats offered the high-profile keynote speech slot to a black politician. Rep. Harold Ford Jr. spoke in 2000.

U.S. Senate candidate Barack Obama and his wife Michelle wave to delegates after he delivered his keynote address to the Democratic National Convention in Boston Tuesday.
(AP photo)

Obama acknowledges he was chosen partly because he is black and the Kerry campaign hopes to bring more minority voters to the polls. But Obama said he also was chosen because he won Illinois' Senate primary with support that crossed racial and geographic lines. His prospects for the fall look good, as his Republican opponent withdrew after a sex scandal and the party has yet to appoint a replacement.

He drew laughter and applause with a reference to himself as "a skinny kid with a funny name who believes that America has a place for him, too." His name is pronounced Oh-bah-ma.

Kerry has the values and record to offer the help that people deserve on everything from rising health care costs to jobs going overseas to civil liberties being threatened, he argued. And he reinforced a frequent message of the convention by promising that Kerry would not hesitate to use military force when necessary.

"We have real enemies in the world," he said. "They must be pursued - and they must be defeated. John Kerry knows this."

He argued against dividing America into liberal and conservative, black and white for political gain.

"In the end, that's what this election is about. Do we participate in a politics of cynicism or a politics of hope?" Obama asked. "John Kerry calls on us to hope."

Obama said the people he meets around Illinois don't expect the government to solve all their problems. "They know they have to work hard to get ahead - and they want to," he said.